Various devices are known in the art for draining and collecting fluids from body cavities, including collection systems specifically designed for urinary bladder drainage. Most such urine collection devices are simple in design, consisting of a flexible catheter duct connected to a urine receptacle. The catheter duct is inserted through the urethra into the urinary bladder, and urine flows in small quantities as it is produced through the catheter into the receptacle. Unfortunately, these conventional drainage devices often become contaminated during use and infection then ascends in a retrograde manner from the collection receptacle to the patient via the catheter duct. Conventional catheter designs also permit back flow of urine from the receptacle into the bladder, particularly when the catheter duct is elevated above the bladder. Moreover, the urine can remain stagnant in the indwelling catheter of existing devices for extended periods, where microorganisms quickly proliferate at body temperatures. Because the urethra cannot close with existing catheters, catheterized patients experience notoriously high rates of urinary tract infections. None of the current catheter designs simulate the normal urethra, which collapses after urination to expel residual urine, nor do they provide a means for preventing bacterial ingress from the catheter into the urinary bladder.
Evacuator-type drainage devices have been designed to minimize the back flow of fluid from the receptacle. Examples include U.S. Pat. Nos. 2,397,257 (Goland et al.), 3,774,611 (Tussey et al.), 3,875,941 (Adair), 4,141,361 (Snyder), 4,981,474 (Bopp et al.), and 5,019,059 (Goldberg et al.), disclosing bellows-type collection receptacles which act as reservoirs for receiving and collecting the body fluids. These collapsible bellows-type receptacles collect fluid as they return to their original shape. As additional fluid is collected, the weight of the fluid expands the bellows container thereby creating additional partial vacuum to draw additional fluid into the receptacle. None of these devices, however, prevent microbial ingress from this stale fluid into the body cavity. Assuming the negative pressure is generally sufficient to withdraw fluid from the indwelling duct, the suction mechanism can fail during operation (e.g., during handling or emptying of the receptacle) causing retrograde leakage of contaminated fluid into the catheter duct. The potential for infection is further increased with evacuator-type drainage devices since these devices typically require periodic opening to purge fluid and resume the suction, thereby exposing the closed drainage system to the surrounding atmosphere. Finally, the catheter duct in these devices can crimp adjacent to the receptacle in such a way that flow into the receptacle is inhibited, subsequently increasing the risk of back flow and infection.
Other "improved" drainage devices employ check valves which are positioned between the catheter duct and fluid receptacle and are designed to minimize back flow of fluid from the receptacle. Most existing check valves consist of a rubber tube sealed in the inlet neck of the receptacle and projecting into the receptacle. The walls of the valves are normally collapsed to prevent reverse flow but open to permit the flow of fluid into the receptacle under pressure. Examples include U.S. Pat. No. 3,298,370 (Beatty) which discloses a shielded check valve to minimize accidental closures, U.S. Pat. No. 3,312,221 (Overment) which discloses an improved "flutter" valve, and U.S. Pat. No. 3,967,645 (Gregory) which discloses a rigid plastic valve having increased sensitivity to back pressure. Although drainage devices having check valves at the receptacle inlet may successfully minimize back flow of receptacle contents into the catheter duct, such devices are deficient in several respects. First, as with other prior art drainage devices, the catheter ducts often become contaminated during use and infection then ascends in a retrograde manner into the urinary bladder. The catheter duct thus provides an open passage for bacterial ingress into the urinary tract. Second, urine can remain stagnant for extended periods in the indwelling duct, where bacteria quickly proliferate at body temperature. While these check valves may reduce back flow from the receptacle, they do not prevent back flow of contaminated urine from the duct into the bladder. Urinary tract infections are therefore common in patients using such drainage devices. Third, because the check valves in these devices are positioned at the distal end of the catheter duct, the valves themselves are susceptible to accidental closure from external pressure. Outside forces, including the patient or his clothing, may bear on the valve in such a way that flow into the receptacle is inhibited and back flow may occur because the valve is effectively held closed.
U.S. Pat. No. 3,800,795 (Walker) discloses another "improved" urinary drainage collecting device, the improvement comprising a leaf-type check valve at the receptacle inlet to prevent back flow and a complex ventilation system designed to minimize urine in the catheter duct. This design, however, suffers from the aforementioned disadvantages, namely those associated with an indwelling, non-collapsible catheter duct and an external check valve at the receptacle inlet.
A need therefore exists for a device for draining urine from incontinent patients which simulates the normal, non-catheterized urethra. Specifically, a need exists for a device which collapses after urination to expel residual urine from the urethral cavity, eliminates urine back flow into the bladder, and minimizes the risk of retrograde infection from the drainage device into the urinary tract.